The use of optical fibers as media for transmission of digital data is becoming more popular due to the high reliability and the large available bandwidth. Traffic in short-reach networks such as metro, access, and data center networks is growing significantly and will likely dominate traffic in long-haul networks. As a result, there is a need for high-capacity optical transceivers designed for short-reach networks. Short-reach networks may refer to networks with relatively short transmission distances and may have no repeaters. Long-haul networks may refer to networks with transmission distances of hundreds or thousands of kilometers (km) and may require repeaters. Metro networks may refer to networks with transmission distances in between short-reach networks and long-haul network and may or may not have repeaters.
The Institute of Electrical and Electronics Engineers (IEEE) is developing a 400 gigabit per second (Gb/s) Ethernet standard that implements intensity modulation and direct detection (IM-DD) using 8 or 16 channels. However, the need for data rates reaching 1 terabit per second (Tb/s) and higher, IM-DD will require an impractical number of channels.